Sound locator receiver



May 23, 1939. F. R. H OUSE SOUND LOCATOR RECEIVER Original Filed July 19, 1934 2 Sheets-Sheet l "Wil,

@MNH f?, Hol/6E May 23, 1939. F. R. HOUSE SOUND LOCATOR RECEIVER Original Filed July 19, 1934 2 Sheets-Sheet 2 IEN R 2 I'QHNK #0l/6E I. /S A O NE atented May 23, 1939 SOUND LOCATOR RECEIVER Frank R. House, Baldwin Harbor, N. Y., assignor to Sperry Gyroscope Company, Inc., Brooklyn, N. Y., a corporation of New York Original application July 19, 1934, Serial No.

735,989. Divided and this application February 28, 1936, Serial No. 66,158

17 Claims. (Cl. 181-26) This invention relates to apparatus for locatng aircraft or other moving targets at night by means of sound. More particularly, it pertains o the construction of the sound receiving devices r horns, the main object of the invention being o improve the construction of such horns, Wherey a smaller, lighter and more eiiicient unit is lrovided and greater efciency secured.

According to the practice prior to my invenon, four large horns constructed throughout on he exponential principle were employed on the heory that great range is secured through great mpliflcation. Each of such horns was on the rder of 3 feet in diameter at the mouth and feet in length, with a sound track length of bout 18 feet. The four horns, as mounted, ocupied about 12 feet square. This construction s based upon the theory that increased range is btained by large amplification. By careful reearch, however, I have found that range is not nproved by ampliilcation alone and, in fact, is Dmetimes reduced thereby, especially if straight ne amplication is used, for which the expoential type of horn was designed. The range f a sound locator depends primarily on the conrast between the ambient or general background oise and that which an airplane adds to it. Amlii-lcation increases the sound level of both the mbient and the airplane sound, but the contrast emains substantially the same. ne amplification seems to the ear actually to icrease the low tones of the background at a reater ratio than the higher tones of the aircraft oise, so that less contrast is obtained and the perator is confused on comparing what he hears nrough his head piece and by his ears Without id and may be led to believe he hears an air.- lane when none is there.

My invention is therefore aimed primarily to aduce the ambient noise. kSuch noise may be lassified as due to two main causes: (1) the oise generated at a distance and carried to the eceiver by sound waves, and (2) the sound genrated within or at the receiver itself, either nrough the mechanical vibration of the receiver r due to wind. One object of my invention is to void over-emphasizing the ambient low tones by onstructing the horns with non-linear amplicaion characteristics such that the timbre of the mplified background noise sounds essentially ne same to the ear as the direct sound.

Another object of my invention is to secure reater efficiency and range by carefully insulatig the sound track structure from the support `,self so that no noise from the movements of Large straight By employing these principles, the size of the horns may be greatly reduced and the exponential construction is largely abandoned. Instead I use a more or less' conical construction of thev main horns with a short sound track length (about 10 feet). With this construction, the higher notes are amplified at a somewhat greater ratio than the lower notes, so that the timbre of the ampliied sound to the ear remains undistorted. I have also eliminated one of the four horns of the prior construction, thus securing a lighter machine without sacrificing efficiency. In addition, I prefer to give the horn mounting a resilient mounting in order to aid in scanning.

This application is a division of my prior application Serial No. 735,989, filed July 19,' 1934, for System of locating aircraft `at night.

Referring to the drawings, illustrating several forms my invention may assume,

Fig. 1 is an elevation of one form of sound locator.

Fig. 21s a perspective view of the preferred form of sound locator horn before the iinal covering of sound absorbing material has been applied thereto.

Fig. 3 is a sectional detail of one of the sound iilters preferably employed in the sound track between the horn and receiving `helmet or ear pieces.

Fig. 4 is a front view, partly in section, oi. a slightly modied form of sound locator.

Fig. 5 is a vertical section of the complete horn shown partially assembled in Fig. 2.

Fig. 6 is a detail of the mounting shown in Fig. 4.

According to my invention, the sound locator comprises a suitable arrangement of listening or sound collecting horns I, 2 and 3 mounted for both turning in azimuth and tilting in elevation. By employing only three instead of four horns, a saving in weight is effected and additional space secured near the base of the instrument. The horns are shown as mounted on a pedestal 4 on a box-like housing 5 which contains the sound lag correction and other apparatus forming no part of the present invention. The entire box is preferably rotatably mounted on a pedestal 6 and is shown as rotated from the azimuth handwheel 1 through gearing 8 and pinion 9, which meshes with a large gear I0 xed to the pedestal 6. 'I'he rotation of the handwheel therefore rotates the horns in azimuth and carries the observers or listeners seated on extensions II and i2 with the horns. The elevation control is shown as eected through a handwheel i 3 which is shown as turning a pinion I4 through gearing i6. Said pinion rotates a gear I6 mounted on cross shaft I1 at the top of the pedestal and to which is secured at the opposite end a bracket I8 carrying the framework I9 which supports the three horns.

'Ihe three horns are shown as 'mounted in the form of a right triangle on the framework I9, With the center or common horn 2 vertically in line with and above the horn I and horizontally in line with the horn 3. Preferably, the vertical and horizontal axes of rotation of the horns bisect the legs of the triangle, so that each horn is the same distance from its axis of rotation. 'Ihis maintains both horns at the same distance from the source of sound, which is important where the two horns are used to compare the intensity of sound received. The azimuth observer on seat II has his receiver or helmet 20 connected through tubing 2| land 22 to the horns 2 and 3, respectively, while the elevation observer at I2 has his helmet 23 connected through tubing 24 and 25 with horns I and 2, respectively, so that the horn 2 at the right angle of the triangle acts as a common horn for both listeners.

Preferably the framework I9 has a slightly oscillatory connection to the bracket I 8, the same being shown as connected thereto through a leaf spring 26 which connects the apex of the triangle to the bracket. This permits a limited oscillation of the horns in both planes or, -in other words, about the axis of the transverse shaft I9' which is rotatably mounted within the bracket I 8, thereby increasing the field of hearing and sensitivity of the device. In other Words, by giving the horns a vibratory motion in both azimuth and elevation, the keenness of perception of the operators is increased by giving them continuous comparison of the intensity of the sound being received. While no attempt is made to illustrate the comparative length of the sound tracks 2|, 22, 24 and 25, it will be understood that in both Figs. 1 and 4 the sound tracks are preferably of substantially the same length.

In Fig. 4 a slightly modified form of mounting is shown, but the horns are again mounted in the shape of a right triangle with the common horn at the right angle or apex of the triangle. In this case the triangular framework I9 is replaced by a hollow curved arm 21 which supports at its two ends the horns I and 3 and, adjacent the center, the central horn 2. In this case the connecting tubes 2| and 25' are carried entirely within the metallic structure of arm 21 between the horns and points of emergence 28 near the axis of rotation of the cross shaft I1', which carries the bracket I 8'. Preferably, also, sound absorbing material 51 is placed within the arm 21 around the tubes 2| and 24'.

The framework or arm 21 is shown as bolted at spaced points 29 and 30 to a resilient plate 3| which, in turn, is bolted at spaced points 32 to the bracket I8. Therefore the horn structure is free to oscillate in both azimuth and elevation through a limited angle for the same purpose as effected by the' spring 26 in Fig. 1. If desired, the structure may be locked to prevent this oscillation by means of a U-shaped bracket 33 pivoted on shaft 34 and having vfriction faces 35 and 35 adapted to bear against flattened surfaces 36 and 36' on the horn structure. When in the position shown in Fig. 6, no oscillation can occur and in case oscillation is desired, the handles 31 and 31' are gripped by the operator and the bracket swung downwardly to release the horn framework from locking engagement with the surfaces 35 and 35.

The preferred form of construction of the horns per se is shown in Figs. 2 and 5. In this constructionl the horn itself is made smaller than the usual exponential horn and is carefully stream-lined and 'sound-proofed to avoid transmitting extraneous sounds, such as due to cross winds or to vibrations of the support itself, to the ears of the listeners. Each horn is preferably built up with a conical shaped interior 33, preferably made of Wood and having a rolled or bell mouth 48. Adjacent the rear end is placed a `supporting ring 4I and light flexible ribs 42 of wood or similar material are connected at front and back between the aring bell mouth 40 and ring 4|. Around the entire structure is placed a smooth covering 43 (see Fig. 5) which encloses completely the inner horn, the outer ribs 42 and the sound track housing 44 connecting the throat 45 of the horn with one of the connecting tubes 22' leading the sound tothe listener. Between said cover and horn there is placed a corrugated sound absorbing material 46 or glass wool.

The entire horn is shown as supported on the metallic framework 21 through a U-shaped bracket 41 having a tubular projection 48 and a collar 48 at its base adapted to be secured to a collar 49 on framework 21. The U-shaped arms on said bracket are secured only to central points 50, 5|, etc., of adjacent ribs 42 so that whatever vibration is transmitted to the bracket will be damped out before reaching the sound track or horn proper. To this end, it should be noted that thev sound track passage, including housing 44 and wooden tube 44', is spaced at all points from the metal bracket. See the annular space 52 between the sound track passage and the part 48. Also, the tube 22 is shown as having the interior thereof connected to the interior of passageway 44' through a hole 53 in soft rubber nipple 54 mounted in the interior of the collar 49. By this means, no vibration reaches the horn or the sound track passages therein.

I am aware that the smaller horns 39 and shorter sound track do not give as true lineal amplification nor as great amplification as usually employed. But this is intentional because, as stated hereinbefore, I find that by amplifying the higher notes more than the lower, the ear is better able to distinguish the aircraft noises from the ambient noise, and by reducing the latter, especially that portion originating in or at the locator itself, good range is obtained without the great size and weight of prior receivers. The conical shape of the forward portion of the horn is preferred as it does not taper down as rapidly as a true exponential horn and therefore the size of the mouth may be made smaller without increasing the amount of air friction on the walls.

Preferably, also, I employ sound filters 56 between the horns and the helmets (see Figs. l l

and 3). Such lters are adjusted to filter out sounds of diiferent pitch from the normal pitch of the propeller and engine drone of an aircraft. With such filters the operator is not confused by extraneous noises.

As many changes could be made in the above construction and many apparently widely diiferent embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Having described my invention, what I claim and desire to secure by Letters Patent is:

l. In a sound locator having spaced sound receivers, a frame supporting the same in spaced relation laterally and in elevation, with azimuth and elevation head phones connected to said receivers, of means for mounting said frame for turning in azimuth and elevation,l and a resilient metallic plate connection in said means adapted to maintain oscillation of said receivers through a limited angle.

2. In a sound locator having three spaced sound receivers, a frame supporting the same in spaced relation laterally and in elevation, with azimuth and elevation head phones each connected to one receiver and individually connected to the other two, of means for mounting said frame for turning in azimuth and elevation, including a resilient metallic plate connection permitting oscillation of said receivers in both planes.

3. In a sound locator having spaced sound receivers, a frame supporting the same in spaced relation laterally and in'elevation, with azimuth and elevation head phones connected to said receivers, of means for mounting said frame .for turning in azimuth and elevation, and a resilient metallic spring plate connection in said means supporting the same at an acute angle to the horizontal, whereby limited oscillation is permitted both in azimuth and elevation.

4. In a sound locator having spaced sound receivers, a frame supporting the same in spaced relation laterally and in elevation, with azimuth and elevation head phones connected to said receivers, of means for mounting said frame for turning in azimuth and elevation, a resilient metallic spring leaf connection in said means adapted to maintain oscillation of said receivers through a limited angle, and means for locking out said resilient connection at will.

5. A sound receiving horn for sound locators, comprising an interior conical horn having a flaring mouth, a spaced* outer covering also of generally conical shape and connecting at its lower end to said mouth, a supporting hollow frame for said horn, and a sound track passage leading from the apex of said horn and curved backwardly on itself to a midway point within said frame and which is between the exterior of said inner horn and the covering thereof, said sound track emerging through said outer covering at said midway point.

6. A sound receiving horn for sound locators comprising an interior conical horn, a spaced outer covering, a supporting hollow frame for said horn, a sound track passage leading from the apex of said horn to within said frame and which is between the exterior of said inner horn and the covering thereof, sound track tubing within said frame and connected to said passage, and sound proofing material between said tubing and frame.

7. A sound receiving horn for sound locators comprising an interior conical horn and a spaced outer generally conical covering therefor, a flaring mouth connecting said horn and covering at the open end, and sound proofing material between said horn and covering, the whole being stream-lined to prevent wind noises.

8. In a sound locator having a plurality of spaced horns, and head phones connected thereto, characterized by each horn beingstream-lined and sound proofed against extraneous noises, and sound filters in the connections between said phones and horns to exclude noises of a pitch dissimilar to that emitted by the target.

9. In a sound locator, three sound receivers arranged in the form of a right triangle with one leg vertical and the other horizontal at the upper end of the vertical leg, an elevation following ear piece having connections to the receiver at the right angle of the triangle and to the receiver vertically in line therewith, an azimuth following ear piece having connections also to said receiver at the right angle and to the receiver horizontally in line therewith, and means for mounting said receivers for turning about vertical and horizontal axes which bisect the horizontal and vertical legs of the triangle.

10. A sound receiver horn for sound locators comprising an interior substantially conical nonmetallic member, a resilient, non-metallic, ribbed framework surrounding said member, spaced therefrom and supporting said member adjacent the iront and back only, and a metal bracket adapted to be secured to the main support and supporting said horn by being connected to mid points of said ribbed frame.

11. A sound receiver horn as claimed in claim 8, having a sound track passage from said member to a sound tube within said outer covering, and sound absorbing material between said bracket and tube.

12. A sound receiving horn for sound locators, comprising an interior conical horn, a spaced outer covering, a supporting frame for said horn, a sound track passage leading from the apex of said horn to within said frame and which is between the exterior of said inner horn and the covering thereof, and sound absorbing means for supporting said horn from the metallic support through said frame.

13. A listening horn for sound locators having a substantially conical hollow main body provided with a substantially conical sound receiving horn therein and a relatively short hollow sound track member extending from the apex of said horn and confined wholly within said main body, whereby said horn has a non-linear amplication characteristic such that the timbre of the amplified sound is distorted toward the higher tones, whereby the apparent distortion toward the lower tones, that otherwise occurs, is avoided.

14. In a sound locator, three spaced sound receivers, a hollow curved arm supporting the same in spaced relation laterally and in elevation, azimuth and elevation head phones, connecting tubes extending between said head phones and said receivers for connecting one receiver to both of said phones and the other receivers respectively to said phones, portions of said tubes being contained within said arm, sound absorbing material surrounding the thusly contained portions of said tubes, and means for mounting said arm. for turning in azimuth and elevation.

15. In a sound locator, spaced sound receivers. tubular supporting means for supporting the same in spaced relation laterally and 1n elevation, azimuth and elevation head phones, connecting tubes extending between said head phones and said receivers, portions of said tubes extending within said tubular supporting means, insulation within said tubuular supporting means and surrounding said enclosed portions of said tubes, and vibration damping material included in the connection between said enclosed portions of said tubes and said receivers.

16. A sound receiving horn for sound locators, comprising an interior substantially conical horn, a spaced outer covering, a supporting bracket for said horn, vibration damping means between said bracket and said horn, and a hollow tapered member providing a sound track arsenal passage leading from the apex o1 said horn to within said bracket, said tapered member ex tending between the exterior of said interior horn andthe covering thereof.

17. A sound receiving horn for sound locators, comprising an interior substantially conical horn, a spaced outer covering, sound insulation between said horn and covering, bracket supportlng means extending inwardly through said cov- -ering for supporting said horn, vibration damping means included between said bracket supporting means and said horn, and a sound track housing extending from the apex o1' said horn reversely and along the exterior of said horn Within said covering to within said supporting means for connection to a connecting tube.

FRANK R. HOUSE. 

